Here’s how:
1: Draw a square on top of the pizza box, 3cm in from the edges, and cut along three of the sides to make a flap.
2: Cover the flap with foil with the shiny side facing out. Use tape or glue to make it stick. Press out any wrinkles with your fingers.
3: Cover the inside of the box (the bottom and the sides) with foil in the same way, shiny side up.
4: Now for the difficult part: pull down the lid, leaving the flap open, and cover the hole with plastic. Use a piece of plastic that’s bigger than the box so that you can seal it tightly. This is to ensure that air cannot get out.
5: Place a piece of black paper over the foil inside the box – your oven is now ready. To start the cooking process, place your viennas on a square piece of foil (or a paper plate) in the centre of the oven.
6: Put the oven in a flat, sunny spot. Close the lid and prop the flap open with a straw. Turn the flap towards the sun – you want its rays to reflect off the foil and into the box. Letthe viennas cook until they are ready. Be patient; it may take 30 minutes to an hour before they are done.

TIPS
• The sunnier the day, the better your oven will work.
• Keep adjusting and turning the box so that the flap is always facing the Sun.
• Be careful, the oven can get very hot.
• Try using marshmallows on top of Marie biscuits in your oven for a sweet treat.